Predictive modeling of atmospheric nuclear fallout microphysics.

The capability to predict size, composition, and transport of nuclear fallout enables public officials to determine immediate and prolonged guidance in the event of a nuclear incident. Predictive computer models of fallout can also provide useful insight for nuclear forensic response when detailed radiochemical processes can be reliably included. Current post-detonation nuclear fallout models prescribe particle size distributions empirically or semi-empirically, based on measurements across limited conditions pertaining to tests conducted primarily in Nevada and the Pacific. These empirical fallout relationships may be subject to large uncertainties in particle size and radionuclide activity distribution if used to extrapolate to other regions with different environmental conditions (e.g., urbanized areas). Replacing empirical relationships with physics-based microphysical process modeling can enable significant advances in the fidelity of predictive models simulating distributions of fallout across diverse environments. Particle microphysics describes the formation and evolution of fallout particles, as well as the interaction of radioactive material with entrained particles, which requires accounting for fundamental processes such as nucleation, condensation, and coagulation. The objective of this perspective article is to summarize computational techniques to simulate particle microphysical processes advancing the fidelity of predicting nuclear fallout. We review current empirical models for simulating post-detonation fallout and assess promising research directions moving towards physics-based predictive systems.

Evaluating the impact of COVID-19 on DXA waiting lists and osteoporosis prescription trends in England 2019-2023.

This study uses NHS waiting times and osteoporosis medication community prescription datasets to assess the impact of COVID-19 on DXA waits and osteoporosis medication patterns in England. Results show significant increases in DXA waiting list times and variation in prescription rates. Investment is needed to improve waiting list times. PURPOSE: This study investigates the impact of COVID-19 on DXA scan waiting lists, service recovery and osteoporosis medication prescriptions in the NHS following the March 2020 national lockdowns and staff redeployment. METHODS: Data from March 2019 to June 2023, including NHS digital diagnostics waiting times (DM01) and osteoporosis medication prescriptions from the English Prescribing Dataset (EPD), were analysed. This encompassed total waiting list data across England's seven regions and prescribing patterns for various osteoporosis medications. Analyses included total activity figures and regression analysis to estimate expected activity without COVID-19, using R for all data analysis. RESULTS: In England, DXA waiting lists have grown significantly, with the yearly mean waiting list length increasing from 31,851 in 2019 to 65,757 in 2023. The percentage of patients waiting over 6 weeks for DXA scans rose from 0.9% in 2019 to 40% in 2020, and those waiting over 13 weeks increased from 0.1% in 2019 to 16.7% in 2020. Prescription trends varied, with increases in denosumab, ibandronic acid and risedronate sodium and decreases in alendronic acid, raloxifene hydrochloride and teriparatide. A notable overall prescription decrease occurred in the second quarter of 2020. CONCLUSION: COVID-19 has significantly increased DXA scan waiting lists with ongoing recovery challenges. There is a noticeable disparity in DXA service access across England. Osteoporosis care, indicated by medication prescriptions, also declined during the pandemic. Addressing these issues requires focused investment and effort to improve DXA scan waiting times and overall access to osteoporosis care in England.

Expectations and outcomes of varying treatment strategies for CML presenting during pregnancy.

Diagnosing chronic myeloid leukaemia (CML) during pregnancy is rare. Tyrosine kinase inhibitors (TKIs) have traditionally been contraindicated owing to their teratogenicity. Management decisions should consider the risks to mother and foetus of uncontrolled disease and teratogenic medications. Further cases are required to build upon the paucity of current literature. We report 22 cases of CML diagnosed during pregnancy from 2002 to date. Twenty-one pregnancies resulted in healthy babies and one patient miscarried. Some patients remained untreated throughout pregnancy but the majority received one or both of interferon-α and leucapheresis. One patient was started on imatinib at Week 26, and one on hydroxycarbamide in the third trimester. We report haematological parameters during pregnancy to provide clinicians with realistic expectations of management. There were no fetal abnormalities related to treatment during pregnancy. Seventeen patients achieved at least major molecular response on first-line TKI. A diagnosis of CML during pregnancy can be managed without significant consequences for mother or child. Leucapheresis and interferon-α are generally safe throughout pregnancy. Despite having been avoided previously, there is growing evidence that certain TKIs may be used in particular circumstances during the later stages of pregnancy. Future work should aim to further elucidate this safety profile.

Leveraging the Full Continuum of Care to Prevent Opioid Use Disorder.

Substance use disorder prevention programs are most effective when matched appropriately to the baseline risk of the population. Individuals who misuse opioids often have unique risk profiles different from those who use other substances such as alcohol or cannabis. However, most substance use prevention programs are geared toward universal audiences, neglecting key inflection points along the continuum of care. The HEAL Prevention Cooperative (HPC) is a unique cohort of research projects that represents a continuum of care, from community-level universal prevention to indicated prevention among older adolescents and young adults who are currently misusing opioids or other substances. This paper describes the theoretical basis for addressing opioid misuse and opioid use disorder across the prevention continuum, using examples from research projects in the HPC.

The Influence of Systemic Inflammation on Treatment Response and Survival in Anal Squamous Cell Cancer.

AIMS: The incidence of anal squamous cell cancer (SCCA) is rising. Although chemoradiotherapy (CRT) provides a chance of cure, a proportion of patients have an incomplete response or develop recurrence. This study assessed the value of inflammation-based prognostic indicators, including the modified Glasgow Prognostic Score (mGPS) and neutrophil:lymphocyte ratio (NLR), in patients with SCCA treated by CRT with curative intent. MATERIAL AND METHODS: Patients with histologically confirmed SCCA were identified from pathology records. Medical records were retrospectively reviewed and clinical, pathological and treatment characteristics were abstracted. The mGPS (0 = normal C-reactive protein [CRP] and albumin, 1 = CRP >10 mg/l and 2 = CRP >10 mg/l and albumin <35 mg/l) and NLR were calculated from routine blood tests obtained prior to CRT. RESULTS: In total, 118 patients underwent CRT for SCCA between December 2007 and February 2018. Of these, 99 patients had appropriate pretreatment blood results available. Systemic inflammation as indicated by NLR >3 and mGPS >0 was present in 41% and 39% of patients, respectively. Most patients had T2 or larger tumours (n = 85, 86%) without nodal involvement (n = 64, 65%). An elevated mGPS was associated with more advanced T-stage (56% versus 35%, P = 0.036). NLR >5 was associated with nodal positivity (56% versus 31%, P = 0.047). On multivariate analysis, more advanced T-stage (odds ratio 7.49, 95% confidence interval 1.51-37.20, P = 0.014) and a raised mGPS (odds ratio 5.13, 95% confidence interval 1.25-21.14, P = 0.024) were independently related to incomplete CRT response. An elevated mGPS was prognostic of inferior survival (hazard ratio 3.09, 95% confidence interval 1.47-6.50, P = 0.003) and cancer-specific survival (hazard ratio 4.32, 95% confidence interval 1.54-12.15, P = 0.006), independent of TNM stage. CONCLUSION: Systemic inflammation, as measured by the mGPS, is associated with an incomplete CRT response and is independently prognostic of inferior survival in patients with SCCA. The mGPS may offer a simple marker of inferior outcome that could be used to identify high-risk patients.

The relationship between aortic calcification and anastomotic leak following gastrointestinal resection: A systematic review.

BACKGROUND: Anastomotic leak (AL) is a significant complication of gastrointestinal (GI) surgery. Impaired perfusion of the anastomosis is thought to play an important role. The degree of aortic calcification (AC) visible on preoperative CT imaging may be associated with an increased risk of AL following GI resection. This review assessed the relationship between AC and AL in patients undergoing GI resection. MATERIALS AND METHODS: MEDLINE, EMBASE and the Cochrane library were systematically searched between 1946 and 2019. Relevant keywords were grouped to form a sensitive search strategy: surgical procedure (e.g. digestive system surgical procedure), calcification (e.g. vascular calcification, calcium score) and outcome (e.g. anastomotic leak). Studies assessing the degree of AC on preoperative imaging in relation to AL in adult patients requiring resection and anastomosis were included. The quality of each study was assessed using the Newcastle-Ottawa scale. Bias was assessed using the RevMan risk of bias tool. RESULTS: Nine observational studies were included: four in patients undergoing oesophageal resection (n = 1446) and five in patients undergoing colorectal resection (n = 556). AL occurred in 20% of patients following oesophagectomy and 14% of patients following colorectal resection. Adjustment for relevant confounders was limited in most studies. Two studies reported a relationship between the degree of AC and AL in patients undergoing oesophagectomy, independent of age and comorbidity. One study reported an association between AC and AL following colorectal resection, while three studies reported higher calcium scores in the iliac arteries of patients who developed colorectal AL. Overall study quality was moderate to good using the Newcastle-Ottawa scale. Detection and reporting bias was evident in the studies examining AL following colorectal resection. CONCLUSION: The current evidence suggests that the degree of AC may be associated with the development of AL, in particular in patients undergoing oesophagectomy. Further prospective data with adequate adjustment for confounders are required. PROSPERO REGISTRATION NUMBER: CRD42018081128.

The relationship between sarcopenia and survival at 1 year in patients having elective colorectal cancer surgery.

BACKGROUND: Colorectal cancer remains a common cause of cancer death in the UK, with surgery being the mainstay of treatment. An objective measurement of the suitability of each patient for surgery, and their risk-benefit calculation, would be of great utility. We postulate that sarcopenia (low muscle mass) could fulfil this role as a prognostic indicator. The aim of this study was to determine the relationship between sarcopenia and long-term outcomes in patients undergoing elective bowel resection for colorectal cancer. METHODS: One hundred and sixty-three consecutive patients who had elective curative colorectal resection for cancer were eligible for inclusion in the study. Psoas muscle mass was assessed on preoperative computed tomography scan at the level of the L3 vertebra and standardised for patient height (total psoas index, TPI). Sarcopenia (low muscle mass) was defined as < 524 mm2/m2 in males and 385 mm2/m2 in females. In addition to clinical-pathological parameters, postoperative complications were recorded and patients were followed up for mortality for 1 year after surgery. RESULTS: Sarcopenia was present in 19.6% of the study participants and was significantly related to body mass index (p = 0.007), 30-day mortality (p = 0.042) and 1-year mortality (p = 0.046). In univariate analysis, American Society of Anesthesiologists grade (p = 0.016), tumour stage (p = 0.018) and sarcopenia (p = 0.043) were found to be significant independent predictors of 1-year mortality. CONCLUSIONS: This study has found sarcopenia to be prevalent in patients with colorectal cancer having elective surgery. Independent of age, sarcopenia was associated with poorer 30-day mortality and survival at 1 year. Measurement of muscle mass preoperatively could be used to stratify a patient's risk, allowing targeted strategies such as prehabilitation, to be implemented to modify sarcopenia and improve long-term outcomes for patients.

Investigation of the changes in hydrogen bonding accompanying the structural reorganization at 103†K in ammonium iodate.

Neutron powder diffraction has been used to observe the changes in hydrogen bonding that occur as a function of temperature in ND4IO3 and, thus, determine the structural features that occur during the low-temperature (103 K) phase transition. It is shown that in the deuterated material the change is not a phase change per se but rather a structural reorganization in which the hydrogen bonding becomes firmly locked in at the phase transition temperature, and stays in this configuration upon further cooling to 4.2 K. In addition, both the differences and changes in the axial thermal expansion coefficients in the region 100-290 K can be explained by the changes involving both the hydrogen bonding and the secondary I...O halogen bonds.

Determinants of serum 25-hydroxyvitamin d levels in healthy young adults living in the Western Cape, South Africa

Background: Vitamin D deficiency is fast emerging as a global pandemic. In South Africa few studies have been conducted to determine the vitamin D status of the healthy population.Methods: This prospective study with an analytical component investigated vitamin D status of healthy undergraduate students at two time points (winter and summer) at Stellenbosch University. Serum 25(OH)D was determined, anthropometric measurements taken and dietary vitamin D intake estimated (food-frequency questionnaire). Skin tone was determined (Fitzpatrick skin type classification), and a skin reflectometry device used to measure dermal melanin content.Results: Results of 242 students indicated a mean serum 25(OH)D of 63.80 ± 41.35 ng/ml and a high prevalence of vitamin D sufficiency (88%). Significantly more females experienced suboptimal vitamin D levels than males (18 vs. 5%; p < 0.01). Participants with lighter skin tones had higher levels of 25(OH)D than those with darker skin tones (chi-square = 24.02; p = 0.02). The majority (60.74%) had a normal BMI, although there was no significant relationship between BMI and serum 25 (OH)D (Spearman's r=­0.11; p = 0.09). Total mean dietary vitamin D intake was 7.99 ± 13.81 mcg, with 87.2% having inadequate intake (< 15 mcg). The relationship between total vitamin D intake and serum 25(OH)D was found to be significant in winter (p < 0.001) and summer (p = 0.01). Serum vitamin D levels were significantly higher in the winter phase (p < 0.001).Conclusions: A low prevalence of vitamin D deficiency was found amongst healthy young adults, despite low dietary vitamin D intakes. Significant relationships were found between serum 25(OH)D and gender, skin tone and vitamin D intake. Further studies need to be conducted, especially in high-risk groups, before results are applied to the greater South African public

Development of small particle speciation for nuclear forensics by soft X-ray scanning transmission spectromicroscopy.

Synchrotron radiation spectromicroscopy provides a combination of submicron spatial resolution and chemical sensitivity that is well-suited to analysis of heterogeneous nuclear materials. The chemical and physical characteristics determined by scanning transmission X-ray microscopy (STXM) are complementary to information obtained from standard radiochemical analysis methods. In addition, microscopic quantities of radioactive material can be characterized rapidly by STXM with minimal sample handling and intrusion, especially in the case of particulate materials. The STXM can accommodate a diverse range of samples including wet materials, complex mixtures, and small quantities of material contained in a larger matrix. In these cases, the inventory of species present in a sample is likely to carry information on its process history; STXM has the demonstrated capability to identify contaminants and sample matrices. Operating in the soft X-ray regime provides particular sensitivity to the chemical state of specimens containing low-Z materials, via the K-edges of light elements. Here, recent developments in forensics-themed spectromicroscopy, sample preparation, and data acquisition methods at the Molecular Environmental Science Beamline 11.0.2 of the Advanced Light Source are described. Results from several initial studies are presented, demonstrating the capability to identify the distribution of the species present in heterogeneous uranium-bearing materials. Future opportunities for STXM forensic studies and potential methodology development are discussed.

An evidence-based treatment algorithm for colorectal polyp cancers: results from the Scottish Screen-detected Polyp Cancer Study (SSPoCS).

OBJECTIVES: Colorectal polyp cancers present clinicians with a treatment dilemma. Decisions regarding whether to offer segmental resection or endoscopic surveillance are often taken without reference to good quality evidence. The aim of this study was to develop a treatment algorithm for patients with screen-detected polyp cancers. DESIGN: This national cohort study included all patients with a polyp cancer identified through the Scottish Bowel Screening Programme between 2000 and 2012. Multivariate regression analysis was used to assess the impact of clinical, endoscopic and pathological variables on the rate of adverse events (residual tumour in patients undergoing segmental resection or cancer-related death or disease recurrence in any patient). These data were used to develop a clinically relevant treatment algorithm. RESULTS: 485 patients with polyp cancers were included. 186/485 (38%) underwent segmental resection and residual tumour was identified in 41/186 (22%). The only factor associated with an increased risk of residual tumour in the bowel wall was incomplete excision of the original polyp (OR 5.61, p=0.001), while only lymphovascular invasion was associated with an increased risk of lymph node metastases (OR 5.95, p=0.002). When patients undergoing segmental resection or endoscopic surveillance were considered together, the risk of adverse events was significantly higher in patients with incomplete excision (OR 10.23, p<0.001) or lymphovascular invasion (OR 2.65, p=0.023). CONCLUSION: A policy of surveillance is adequate for the majority of patients with screen-detected colorectal polyp cancers. Consideration of segmental resection should be reserved for those with incomplete excision or evidence of lymphovascular invasion.

Occupational burnout among radiation therapists in Australia: Findings from a mixed methods study.

INTRODUCTION: Evidence demonstrates that health care professionals in the palliative care context are more burned out than other health professionals. The aims of this study were to examine: (1) occupational burnout levels among radiation therapists in Australia, (2) association between demographic factors on burnout and (3) radiation therapists' perceptions of burnout. METHODS: A cross-sectional online survey including the Maslach Burnout Inventory was administered to Radiation Therapists in Australia. Data were analysed using SPSS Ver 20 and open ended comments were analysed thematically using Nvivo 10. RESULTS: A total of 200 radiation therapists participated in the survey. RTs had a high mean (±SD) burnout score for emotional exhaustion (38.5 ± 8.2), depersonalisation (17.5 ± 4.7) and personal achievement (30.5.3 ± 4.3) compared to RTs and health workers in other studies. High levels of emotional exhaustion, depersonalisation and low levels of personal achievement were present in 93% (186/200), 87% (174/200) and 61% (122/200) of participants respectively. RTs identified high workload and staff shortages, interpersonal conflict and technology as key sources of stress in the RT work environment. CONCLUSION: Australian RTs' level of burnout on all three stages of burnout exceed previously reported burnout levels for similar cohorts both locally and internationally. It is important that future interventions aimed at minimising or preventing stressors are identified and implemented in the radiation therapy work environment.

Systematic review: the impact of exercise on mesenteric blood flow and its implication for preoperative rehabilitation.

BACKGROUND: Exercise in the preoperative period, or prehabilitation, continues to evolve as an important tool in optimising patients awaiting major intra-abdominal surgery. It has been shown to reduce rates of post-operative morbidity and length of hospital stay. The mechanism by which this is achieved remains poorly understood. Adaptations in mesenteric flow in response to exercise may play a role in improving post-operative recovery by reducing rates of ileus and anastomotic leak. AIMS: To systematically review the existing literature to clarify the impact of exercise on mesenteric arterial blood flow using Doppler ultrasound. METHODS: PubMed, EMBASE and the Cochrane library were systematically searched to identify clinical trials using Doppler ultrasound to investigate the effect of exercise on flow through the superior mesenteric artery (SMA). Data were extracted including participant characteristics, frequency, intensity, timing and type of exercise and the effect on SMA flow. The quality of each study was assessed using the Downs and Black checklist. RESULTS: Sixteen studies, comprising 305 participants in total, were included. Methodological quality was generally poor. Healthy volunteers were used in twelve studies. SMA flow was found to be reduced in response to exercise in twelve studies, increased in one and unchanged in two studies. Clinical heterogeneity precluded a meta-analysis. CONCLUSION: The weight of evidence suggests that superior mesenteric arterial flow is reduced immediately following exercise. Differences in frequency, intensity, timing and type of exercise make a consensus difficult. Further studies are warranted to provide a definitive understanding of the impact of exercise on mesenteric flow.

Disparities in Obesity, Physical Activity Rates, and Breast Cancer Survival.

The significantly higher breast cancer (BCa) mortality rates of African-American (AA) women compared to non-Hispanic (NHW) white women constitute a major US health disparity. Investigations have primarily focused on biological differences in tumors to explain more aggressive forms of BCa in AA women. The biology of tumors cannot be modified, yet lifestyle changes can mitigate their progression and recurrence. AA communities have higher percentages of obesity than NHWs and exhibit inefficient access to care, low socioeconomic status, and reduced education levels. Such factors are associated with limited healthy food options and sedentary activity. AA women have the highest prevalence of obesity than any other racial/ethnic/gender group in the United States. The social ecological model (SEM) is a conceptual framework on which interventions could be developed to reduce obesity. The SEM includes intrapersonal factors, interpersonal factors, organizational relationships, and community/institutional policies that are more effective in behavior modification than isolation from the participants' environmental context. Implementation of SEM-based interventions in AA communities could positively modify lifestyle behaviors, which could also serve as a powerful tool in reducing risk of BCa, BCa progression, and BCa recurrence in populations of AA women.

Applying a Conceptual Framework to Maximize the Participation of Diverse Populations in Cancer Clinical Trials.

The underrepresentation of ethnically diverse populations in cancer clinical trials results in the inequitable distribution of the risks and benefits of this research. Using a case study approach, we apply a conceptual framework of factors associated with the participation of diverse population groups in cancer clinical trials developed by Dr. Jean Ford and colleagues to increase understanding of the specific strategies, and barriers and promoters addressed by these strategies, that resulted in marked success in accrual of racially and ethnically diverse populations in cancer clinical research. Results indicate that the studies presented were able to successfully engage minority participants due to the creation and implementation of multilevel, multifaceted strategies that included: culturally and linguistically appropriate outreach, education, and research studies that were accessible in local communities; infrastructure to support engagement of key stakeholders, clinicians, and organizations serving minority communities; testimonials by ethnically diverse cancer survivors; availability of medical interpretation services; and providing infrastructure that facilitated the engagement in clinical research of clinicians who care for minority patient populations. These strategic efforts were effective in addressing limited awareness of trials, lack of opportunities to participate, and acceptance of engagement in cancer clinical trials. Careful attention to the context and population characteristics in which cancer clinical trials are conducted will be necessary to address disparities in research participation and cancer outcomes. These studies illustrate that progress on minority accrual into clinical research requires intentional efforts to overcome barriers at all three stages of the accrual process: awareness, opportunity, and acceptance of participation.

Plutonium segregation in glassy aerodynamic fallout from a nuclear weapon test.

This study combines electron microscopy equipped with energy dispersive spectroscopy to probe major element composition and autoradiography to map plutonium in order to examine the spatial relationships between plutonium and fallout composition in aerodynamic glassy fallout from a nuclear weapon test. A sample set of 48 individual fallout specimens were interrogated to reveal that the significant chemical heterogeneity of this sample set could be described compositionally with a relatively small number of compositional endmembers. Furthermore, high concentrations of plutonium were never associated with several endmember compositions and concentrated with the so-called mafic glass endmember. This result suggests that it is the physical characteristics of the compositional endmembers and not the chemical characteristics of the individual component elements that govern the un-burnt plutonium distribution with respect to major element composition in fallout.

In Vitro and In Vivo Characterization of a Fully Felinized Therapeutic Anti-Nerve Growth Factor Monoclonal Antibody for the Treatment of Pain in Cats.

BACKGROUND: Limited options are available for the treatment of pain in cats. Monoclonal antibodies (mAbs) that neutralize nerve growth factor (NGF) have demonstrated analgesic capacity in rodent models, people with osteoarthritis, and dogs with degenerative joint disease. HYPOTHESIS/OBJECTIVES: This study describes the design and characterization of a fully felinized anti-NGF monoclonal antibody. In vitro potency, pharmacokinetics, and the ability of the antibody to treat pain in a self-resolving, acute inflammation model were investigated in cats. ANIMALS: Thirty-eight cats at a research colony at Charles River Laboratories, Ireland. METHODS: Felinized anti-NGF mAb, NV-02, was produced using a complementary DNA (cDNA)-based method (PETization). Purified NV-02 was tested for affinity, potency, and immunoreactivity in vitro, then for safety and plasma pharmacokinetic distribution in vivo, and analgesic efficacy in a model of kaolin-induced inflammatory pain. RESULTS: Anti-NGF mAb, NV-02 neutralized NGF with high affinity and potency and did not bind complement. NV-02-administered SC had a plasma half-life of 7-15 days and was well tolerated at dosages up to 28 mg/kg. A dosage of 2 mg/kg NV-02 SC significantly decreased signs of lameness on day 2 (P = .0027), day 3 (P = .016), day 4, (P = .0063), day 5 (P = .0085), day 6 (P = .0014), and day 7 (P = .0034) after induction of inflammation. CONCLUSIONS AND CLINICAL IMPORTANCE: The high affinity, long plasma half-life, safety, and analgesic efficacy of felinized anti-NGF mAb (NV-02) support further investigation of the analgesic potential of this antibody in the cat.

Spatially-resolved analyses of aerodynamic fallout from a uranium-fueled nuclear test.

Five silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U ((238)U/(235)U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < (235)U/(238)U < 11.84 among all five spherules and 0.02 < (235)U/(238)U < 7.41 within a single spherule. In two spherules, the (235)U/(238)U ratio is correlated with changes in major element composition, suggesting the agglomeration of chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between (234)U/(238)U, (235)U/(238)U, and (236)U/(238)U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members.

A method for the monitoring of metal recrystallization based on the in-situ measurement of the elastic energy release using neutron diffraction.

A method is proposed for the monitoring of metal recrystallization using neutron diffraction that is based on the measurement of stored energy. Experiments were performed using deformed metal specimens heated in-situ while mounted at the sample position of the High Resolution Powder Diffractometer, HRPD (ISIS Facility), UK. Monitoring the breadth of the resulting Bragg lines during heating not only allows the time-dependence (or temperature-dependence) of the stored energy to be determined but also the recrystallized fraction. The analysis method presented here was developed using pure nickel (Ni270) specimens with different deformation levels from 0.29 to 0.94. In situ temperature ramping as well as isothermal annealing was undertaken. The method developed in this work allows accurate and quantitative monitoring of the recrystallization process. The results from neutron diffraction are satisfactorily compared to data obtained from calorimetry and hardness measurements.

A combined theoretical and experimental investigation of uranium dioxide under high static pressure.

We have investigated the behavior of uranium dioxide (UO2) under high static pressure using a combination of experimental and theoretical techniques. We have made Raman spectroscopic measurements up to 87 GPa, electrical transport measurements up to 50 GPa from 10 K to room temperature, and optical transmission measurements up to 28 GPa. We have also carried out theoretical calculations within the GGA + U framework. We find that Raman frequencies match to a large extent, theoretical predictions for the cotunnite (Pnma) structure above 30 GPa, but at higher pressures some behavior is not captured theoretically. The Raman measurements also imply that the low-pressure fluorite phase coexists with the cotunnite phase up to high pressures, consistent with earlier reports. Electrical transport measurements show that the resistivity decreases by more than six orders of magnitude with increasing pressure up to 50 GPa but that the material never adopts archetypal metallic behavior. Optical transmission spectra show that while UO2 becomes increasingly opaque with increasing pressure, a likely direct optical band gap of more than 1 eV exists up to at least 28 GPa. Together with the electrical transport measurements, we conclude that the high pressure electrical conductivity of UO2 is mediated by variable-range hopping.